Pickup trucks are motor vehicles with a rear open top cargo area often referred to as a bed. Pickup trucks are popular largely because the bed allows them to be utilized in so many different ways, including carrying a variety of types of cargo and towing various types of trailers. Traditionally the majority of body structures on pickup trucks have been formed from steel alloys. Through years of experience, pickup truck designers have learned how to design steel truck body parts that withstand the variety of demanding pickup truck applications. The current regulatory and economic environment have increased the importance of making pickup trucks more fuel efficient as well as functional and durable. One way to reduce the fuel consumption of a vehicle, especially when unloaded, is to reduce the weight of the vehicle body.
Aluminum alloys generally have a higher strength to weight ratio than steel alloys. Replacing steel with aluminum offers a substantial potential for weight reduction. However, the elastic modulus of aluminum is generally lower than the elastic modulus of steel. Fabrication techniques and methods of joining and reinforcing parts that work well for steel parts may not work well for the same aluminum part. Due to these and other differences, simple material substitution does not necessarily produce an acceptable design.
As shown in FIG. 2, a prior art sill structure for a pick-up truck is illustrated that is formed from steel that is reinforced with a two part stamped steel bracket assembly “A” that is adapted to receive a bolt through a space “S” formed by two semi-circular bends “B”. A bolt (not shown) attaches the bracket assembly “A” to a frame rail “R.” The two part steel bracket “A1” and “A2” must be pre-assembled and welded together off-line. The assembled steel bracket is then welded to a crossbar and the front sill of the pick-up truck bed. Disadvantages of this prior art reinforcement include the fact that multiple parts are required, multiple assembly operations must be performed and the reinforcement is relatively heavy compared to an aluminum part.
Steel brackets may not work as well with aluminum body structure components as with steel body structure components, often requiring the steel brackets to be coated or have other additional processes performed on them or the receiving aluminum structure. Accordingly it would be advantageous to have a structural reinforcement configured to transfer and manage the loads between the pickup box and the frame that also works well with aluminum body structures. It may also be advantageous for the structural reinforcement to aid in preventing adjacent aluminum panels from cracking or deforming due to road load inputs from the frame and cargo loading from the bed. It may also be advantageous for the structural reinforcement to be able to withstand the clamp load of the box to frame bolts.
The above problems and other problems are addressed by this disclosure as will be summarized below.